It is a common problem among car owners worldwide that ignition keys are inadvertently left inside automobiles after the operator has left the automobile, resulting in an ignition key being locked in the car. Since the ignition key is often also the key which operates the automobile door, the automobile must be opened by an alternate key or by special equipment.
The same problem can exist with regard to using keys to unlock homes, offices, etc., where the key for gaining access to the particular compartment can be inadvertently locked inside the compartment.